Spray gun mover and control



May 4, 1954 w.c. BLlFaT SPRAY GUN MOVER AND 4CONTROL 3 Sheets-Sheet l Filed Jan. ll 1951 INVENTOR. W/7//27/77 5px/5 May 4, 1954 w. c. BuRT 2,677,219

SPRAY GUN MOVER AND CONTROL Filed Jan. 11, 1951 3 Sheets-Sheet 2 Il: 32- 33 35`- JLOJ 50 4Q .44. 30 4Z |h|.l||"' E: 2 6

u 474 M Z9 INVEN M @MMM@M May 4, 1954 w. c. BURT 2,677,219

syRAY GUN MOVER AND CONTROL Filed Jan. 1l, 195.1 3 Sheets-Sheet 3 Patented May 4, 1954 SPRAY GUN MOVER AND CONTROL William c. Burt, Olean, N. Y., assignor-to Clair Manufacturing- Company, Inc., Olean, N. Y.

Application January 11, 1951, Serial No. 205,529

9 Claims.

This invention relates to glazing, burnishing, polishing and buffing methods or the like as are useful in the industries in connection With the finishing of metal, plastic, Wooden or other surfaces. More particularly, the present invention relates to improvements in means for transversely moving spray guns such as are used to distribute materials such as abrasives for example over surfaces such as glazing or polishing or buiiing rolls requiring to be uniformly coated With sprayable material. The invention has particular application in conjunction with straight line reciprocating spray gun installations.

Whereas, in prior machines for the purposes aforesaid the spray gun has usually been permitted to spray its material during directional change halts and deceleration and acceleration phases of its traverse movements with consequent overloading of the sprayed surfaces at the ends of the gun travel path, the present invention contemplates control of the gun spray operation independently cf the gun mover operation and complete cessation of the spraying operation during acceleration deceleration and direction reversing movements of the gun. Also, in prior machines for the aforesaid purposes Where the problem has been to spray relatively long polishing rolls, in order to avoid use of impracticably long gun mover cylinders and travel rails two or more guns have been mounted in side-by-side relation upon the traverse motion frame so as to reduce the required length of the traverse stroke, Such installations have been found to be defective however because it is impossible to adjust the gun mover and spray control devices so as to prevent either overlapping or gapping of the spraying operations .of adjacent guns, `and in eitherl case the surfaces being sprayed are overloaded in the 'ons Where the guns are halted and accelerate and decelerate in their traverse movements incidental to reversal of direction of travel. Also, in some prior machines for the purposes the mover cylinder exhaust air has f to feed the gun', and this introduces cylinder oil into the spray solution such as is-not permissible when working for example With Water hase mixtures or emulsions, or thelike.

. @ne of the objects of the present invention is to avoid the difficulties and disadvantages aforesaid by providing improved means for mounting and moving a spray gun in straight line reciprocative manner and to control the spray operation of the so as to insure uniform coverage of the surface being treated despite necessary reversals of direction and changes of pace of the gun' travel incidental to its recpro'cati'on;

Another object of the invention. is to provide in conjunction with a reciprocating spray gun an improved gun air control device whereby the gun discharge may be interrupted at the end of each stroke of the gun movement in improved manner so as to prevent incidental'plugging of the gun whereby smooth and accurate operation of the gun and avoidance of abrasive dripping isassured to provide a, uniform spi-ay delivery pat-A tern.

Another object of the invention is to provide a.

straight linev reciprocating. gun mover mechanism which is of improved compactness of form in relation to the length of traverse.

Another object of the invention is to provide in devices of the character aforesaid improved means for adjusting the mechanism to suit perfoi-mance specifications.

Still another object of the invention is to prov vide in machines of the character described improved means foradjusting relatively moving parts to compensate for wearing thereof.

Other objects and advantages of the invention will appear in the specication hereinafter.

In the drawing:

Fig. l is a front elevation of a 2-r'o1l polishing or glazing machine of a typesuch as is used in the cutlery polishing and glazing industries, hav-V ing mounted thereon an abrasive spray gun mounting and moving and control mechanism of the invention;

Fig, 2 is a fragmentary section, on an enlarged scale, taken along line II-Ilof Fig. 1;

Fig. 3 is an enlarged detail of Fig; 2 ;l

Fig. 4 is a fragmentary section taken along line IV-IV of Fig. 3';

Fig. 5 is a front elevational View showing an other form of spray gun actuating mechanism of the invention;

Fig. 6 is an enlarged detailv of Fig. 5;

Fig. '7 is a fragmentary sectiony on an enlarged scale, taken along line VII-Vil of Fig. 5;

Fig. 8 is a fragmentary section, on an enlarged scale, taken along line VIII-VIII of Fig. 6; and

Fig. 9 is a Wiring control diagram for the machines of Figs. 1 and 5.

As stated hereinabove, the present invention relates to means for motivating and controlling operation of a spray gun orrthe like in conj'unce tion with straight line reciprooative movements thereof Vfor the purpose of effecting uniform dis` tribution of the spray gun output over surfaces to be treated thereby. Theinvention is applicable to any industrybut by. Way of exempl'i'fication it is illustrated: and will be described in' detail"here`-' inaftei" in conjunction with' machines employing 3 paired polishing or bumng rolls between which articles of manufacture are passed for finishing operations thereon While suitable polishing or builing abrasive materials are fed by a gun onto the machine rolls. Thus, as shown in Fig. l, a machine for such purpose may comprise a base structure I mounting bearing pedestals |2-i2 which in turn carry parallel polishing or buing rolls lli-I4. Motors l5-l5 are shown as being connected through suitable shafting to the rolls lLl-U for driving the latter to rotate so as to thereby provide a polishing or buing gap as indicated at i 'i between the rolls for passage therethrough of the work pieces to be surface treated, as is well known in the art. Such work pieces may be individually handled or mounted in gangs upon suitable frames or the like which are in turn mounted upon an upper carriage as indicated at I8 which is arranged to reciprocate from right to left, as viewed in Fig. 1. The carriage I3 is in turn mounted upon a lower carriage i9 which is mounted upon the base l0 by means of slideways 2li-2B for reciprocation in directions transversely of the directions of reciprocation of the upper carriage I8. Thus, the work pieces will be mounted and arranged for simultaneous reciprocation in directions longitudinally of the polishing or buffing rolls and back and forth in and out of the polishing gap Il; the operative details of such a machine for this purpose being more fully disclosed for example in U. S. Patent No. 2,458,708.

A gun for spraying a suitable polishing or buffing abrasive (the various types of which are Well known in the art) is illustrated at 25, and as illustrated in Figs. l-2, the gun may be mounted on the machine by means of a framing structure which extends from the pedestals l2-I 2 and which includes end plates 26-26 and a generally rectangular housing 28 which mounts at its opposite ends upon the end plates 25--26. A slideway 28 extending longitudinally of the housing 28 is xed to the bottom plate thereof and engages a rack bar 30 in such manner that the latter is freely slidable longitudinally within the slideway 29 from right to left as viewed in Fig. l, throughout the extent of the housing 28. A second rack bar 32 is fixed to the ceiling plate portion of the housing 28, and a spur gear 33 is disposed between the racks 30, 32 to Asimultaneously mesh with both racks. The gear 33 is connected by means of a pin and clevis device 34 to a piston rod 35 extending from a cylinder 35 which is mounted within the housing 28 and fixed thereto by means of an end bracket 31. Thus, it will be appreciated that movement of the piston within the cylinder 36 will procure corresponding displacements of the gear 33, thereby causing the latter to rotate and to drive the sliding rack 3i] to move in the same directions as the piston movements but at twice the rate and to twice the extent of such piston movements.

A bracket as indicated at 40 is arranged to extend rigidly from the sliding rack 30 for mounting of the gun 25 and its control valve 42 thereon, so that both the gun 25 and its control valve will move with the sliding rack 30. This may be accomplished as shown by mounting the valve 42 directly on the bracket 40 and then arranging the valve outlet conduit as indicated at 44 to act as a mounting bracket for the gun 25 and also to convey compressed air to the gun. However, it will be appreciated that the gun and valve devices may be mounted in any other suitable manner relative to the moving rack 3o so that they will move with the rack while being at the same 4 time properly positioned for their intended functions as will be explained more fully hereinafter. In any case it will be understood that the arrangement will include provision for intake of compressed air for actuation of the gun, as by means of the conduit 44, and as well as provision for intake of the abrasive supply as indicated for example at 4S. For this purpose the intake fitting 4S may connect to any suitable supply of abrasive, as is well known in the art.

The intake port of the valve 42 is indicated at 48 and is illustrated as being connected by means of a conduit 49 to a suitable compressed air supply line 5E). Preferably, an air lter device of some suitable construction as indicated at 52 will be inserted in the supply line 50 ahead of the conduit 49, for the purpose of removing any oil or other foreign substance from the air leading to the spray gun, such as might become entrapped in the air at the air compressor or elsewhere.

The compressed air supply line 50 also leads through suitable connections to the cylinder 36 for two-way operation of the piston therewithin. For example, a two-way valve device as indicated at 551 may be arranged to control the flow of air from the line 50 into the cylinder 36; the armature of the valve 54 being controlled electrically to permit introduction of compressed air into the cylinder 38 alternately at opposite sides of the piston therewithin. Furthermore, the valve 54 will preferably be electrically operated so as to give the operator of the machine full stop-start control of the machine. Also, a pressure regulator as indicated at 56 and a lubricator as indicated at 58 will preferably be included in the line 5 ahead of the valve and cylinder` 36 so that the air pressure on the cylinder may be manually regulated and so that the air feeding the cylinder 3'6 will be lubricated for proper maintenance of the cylinder-piston unit.

As shown in Fig. l, the gun control valve 42 includes an actuating stem 59 which is arranged to be controlled by means of a cam roller 6U carried by a lever Sl which is fulcrumed upon the valve body. The cam roller 60 is in turn arranged to be actuated by a pair of cam spools 52-64 which are carried upon a rod 55 which is mounted at its opposite ends upon brackets 66--61 extending from the housing 28. The rod t5 is arranged to parallel the rack bar 30 so that the cam devices l52-64 come into registry with the cam roller 60 when the gun 25 reaches the opposite ends of its prescribed travel as it reciprocates in response to operation of the piston-cylinder unit 3B. Thus, the gun is arranged for application of abrasive against the polishing or buing rolls throughout the extent of their Working areas. The cam devices 62-66 are arranged to be adjustable longitudinally on the rod E5 and to be locked thereon at any desired position of adjustment as by set screws 58 (Fig. 4).

Consequently, to set up the machine to process an article or a gang of work pieces of given width a pair of electrical limit switches 69-69 (Fig. 9) may be arranged to control solenoid-actuated cylinder valve 54; the limit switches being set so as to cause the piston rod 35 to move within such limits as will cause the rack 30 to reciprocate throughout a range extending at ea/Jh end beyond the areas of the rolls requiring to be supplied with abrasive throughout the prescribed finishing operation. Then, the cam devices 62-64 will be individually adjusted longitudinally on the rod 65 so that they will coincide with the limits of the U range of travel oi abrasive application by the gun 25as carried by the rack 30.

The cam devices 52-E4 are formed with slop. ing faces as indicated at 10, so that they will somewhat gradually lift the cam roller S as it reaches the desired limit of gun spraying; thereby gradually cutting on? the flow of air to the gun as the gun reaches each end of its range of operation. reduces the air pressure in the gun so as to deprive the gun of sufficient air pressure to continue the feeding of abrasive through the gun nozzle While a small flow of air continues for a short time to pass through the nozzle beforethe valve closes completely. This operates to clean the abrasive feed orifice of thegun incidental to each stoppage of the gun operation, and thus prevents undesirable plugging of the gunw-ith abradesirable piling up of abrasive on the rolls in the l regions of the end limits of the gun travel back and forth along the rolls; and it Will be appreciated that the cam devices 62--6llV may be readily f adjusted on the rod t5 so as to give exactly the proper timing ofthe gun shut off operations. Consequently, with a gun control mechanism of the present invention undesirable piling and cakingof abrasive on the rolls and subsequent spalling oii of caked abrasive from the rolls is prevented, andv this avoids occurrence of alternately abrasive'- coated and bare roll surfaces suchas are so un'- desirable in connection with industrial iinishing opeations.

Asv shown in Figs. 3 and e, further provision for" fine adjustment of the cam devices relative tothe valve actuating cam roller is made in'conjunction with the mounting connections of the outer ends of the rods d5 inthe brackets S and 61. For

example, as shown in conjunction with thebracket 5&3. the latter is apertured to receive a sleeve 'l2 which is eccentric-ally bored to receivev the rod` therein. A shoulder i3 is formed on them-01105;

and it is threaded and provided with a nut andr at its outer endforvr cooperalock washer i tion with the shoulder le to lock the rod and sleeve firmly in the bracket 06. Thus, upon loosening oi the nut 54, the sleeve 'iiimay theree upon be turned so as to displace the'rod4 |35 there'- by adjusting the vertical elevation of the oam'device Sii which is carried bythe rod. Provision of' this type eccentric mounting at each end'of the rod es permits the latter to be adjusted relative tothe valve roller Sii so that any desired' operation of the valve and gun devices may be aoourately obtained.

Figs. 5 to d illustrate application of the invention in another manner to a polishing or glazing machine including side frame members 313-vr upon which are mounted polishing or glazingrolls.`

3 |-8| which correspond to the rolls Ii-I of the machine illustrated in Figs. l-2. Inl Fig, 5fthe; abrasive spray gun is indicated at. l2A andziscarriedf.-

yi'his gradual closing of the valve 42 firstr the area requiring spraying by .means of;v a. compressed air ni'etzzcondutu which extends from connection to the air outlet port of a control valve 8d. The intake port ofthe.

valve 84 is connected to a compressed air supply conduit 85 which in turn leads into connection- 88 upon a cross head member 90 which is mountredfto move within an elongate rectangular housuing 92Which corresponds generally to the housing 28 of Figs. 1-2.

The cross head 00 is mounted to move freely Within the housing 92 by means of rollers 523-94- 95-96; andl as shown in Fig. 8` the rollers are carried by-'axles Sl which are in turn carried within eccentrica-Hy bored sleeves S8. lockV the Wheel and axle units upon the sleeves 08, and the latter are screwthread mounted upon'the crosshead in such manner that the four rollers` `93`949596 are brought to bear respectively against the four inside wall portions of the rectangular housing 92 for supporting the cross head 90 in free rolling relation Within the housing. Thus, it Will be appreciated that the eccentric sleeve devices 58 are adapted to be turned as may be required to adjust the roller axles positionally relative to the cross head, so that the rollers may be thereby accurately positioned relative to the housing so as to support the cross head for free rolling movement therewithin without binding and without lost motions such as would permit thecross head to chatter when moving inside the housing. Thus, this eccentric roller mounting arrangement is useful in connection with initial assembly of the device as Well as comprising means for compensating for Wearing of the rollers or housing members, to insure precise non-chattering operation of the cross head.

Thecross head su is xed to one end of a piston rod |00 which extends into a cylinder |02 whichy is. xed to extend longitudinally within the housing 92. tothe cylinder 3 of Figs. l, 2 and is arranged. to .be controlled by means of a two-Way valve 1'04 which corresponds to the valve 55 of Fig. 1. The

valve. 04 is fed by the air supply line 8S, andas indicated at |06, |il'l, 30E, air filter and pressure regulator and lubricator devices, respectively, are preferably installed in the line 35 ahead of the valve |04. for reasons explained hereinabove in connection with the mechanism of Fig. 1. shown in Fig. 5, the valve Sli is arranged to be controlled by means of a roller arm Ht which is fulcrumed upon the valve housing and arrangedA to register with opposite cam spools ||2| I2 which are slidably mounted for adjustment upon a rod I4 carried by brackets. i. E-I I6 to extend alongside the housing 92 and parallel tothe direction of cross head travel. The cam spools |.|f2.-||2 are shaped to include sloping contact `portions as in the manner of the cam spool 6.4,-62 of Fig. 1 for purposes explained hereinabove. Also, the rod l ifi is elevationally adjustable on the brackets iiE-i i8 by means of l eccentric, lockingv sleeve devices H8 which are.

of type similar to. the sleeve devices shown and described hereinabove in connection with the arrangement of Figs. 1 4.

Thus, it will be appreciated that in the mechanism of Figs. 5 to 8, the spray gun is carried by av cross headv device which is in turn connected directly to theactuating piston of the cylinder which procures reciprocation of the spray gun unit, as distinguished from the spray gun mountir1g=methodz ofi` Figs 1'-21 whereinV4 an intermediate Lock nuts 99v The cylinder 02 corresponds- AsV gear and rack arrangement is employed to multiply the extent of spray gun travel responsive to piston movement. Thus, in the case of the mechanism of Fig. 5, the piston cylinder unit and the housing 92 must of necessity be of sufficient length to at least equal the length of the machine roll which is required to be sprayed with abrasive material, and in the case of relatively short polishing or buiing roll installations the spray gun mounting method or Fig. is quite practicable. However, as explained hereinabove it will be appreciated that the arrangement of Fig. l provides for a path of spray gun travel which is twice as long as the extent of the corresponding piston movement within the cylinder 36; and thus, in the case of Fig. l a piston cylinder and housing unit may be designed to more compact form and is of particular advantage in connection with machines employing relatively long polishing or buiiing rolls. In such cases the piston-cylinder and housing unit may readily be constructed not to exceed the overall width of the other portions of the machine.

However, it will be appreciated that in con-l nection with the machines of both Fig. 1 and Fig. 5, the precise adjustability of the spray gun valve cam control action is attained whereby the machines may be readily adjusted so that the supply of abrasive is automatically reduced and cut oiT in the regions of the ends of the strokes of the spray gun as it travels back and forth alongside the rolls so as to avoid building up of undesirably heavy coatings of abrasive on the rolls at the ends of the spray gun strokes. Also, that the gun spraying operations at the ends of the reciprocatory strokes thereof are interrupted in an improved manner so as to avoid plugging of the gun jets and dripping of abrasive therefrom onto the polishing rolls such as would otherwise be inevitable incidental to interruptions of the gun spraying operations.

As explained hereinabove, whereas the drawing and the detailed description relates specically to application of the invention to Y2-roll glazing or polishing or buiing machines or the like, the invention is equally applicable to other devices wherein the problem is to move the spray gun to reciprocate and to at the same time apply a uniform coating of the sprayed material over the surface being treated. Thus, although. only7 a few forms of the invention have been illustrated and described in detail, it will Vbe understood to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

l. In a spray gun mover mechanism a crosshead member arranged for mounting the spray gun thereon, means for reciprocating said crosshead member for carrying the spray gun in a traverse path, guide rail means paralleling the path of said cross-head in its reciprocative movements, roller means carried by said cross-head and bearing against said guide rail means for frictionless guiding of said cross-head, and eccentric bearing means mounting said roller means upon said cross-head and adjustable at will to displace said roller means relative to said cross-head for takinfy up any slack between said rollers and said guide way such as may be caused by wearing of the roller means or guide rail means.

2. A spray gun mover mechanism comprising 8 a stationary frame, guide rail means mounted on said stationary frame, a nrst gear rack mounted upon said guide rail means for longitudinal shifting movements thereon, bracket means extending from said rst gear rack for mounting the spray gun thereon to reciprocate with said gear rack relative to said stationary frame, a second gear rack fixed to said stationary frame to extend in spaced parallel relation to said iirst gear rack, a gear disposed between said rst and second gear racks to extend in meshing relation therebetween, and a powered push-pull member connected at one of its ends pivotably to the center of said gear and extending therefrom into connection with a push-pull power source, whereby displacements of said push-pull member will force said gear to be displaced relative to said fixed frame and to rotate due to its meshed connection with said second rack to thereupon drive said first gear rack to move at twice the rate of movement of said push-pull member.

3. A spray gun mover mechanism comprising in combination with a spray gun, a stationary frame, a movable structure including a reciprocating member mounting the spray gun to be reciprocatively movable therewith, power means connected to said member for moving the latter so as to reciprocate the gun across the area to be sprayed and slightly therebeyond at each end thereof, a variable delivery valve controlling inlet of compressed air to said spray gun for operation of the latter, control means for said valve, said valve and said control means being respectively connected to the stationary frame and to the movable structure and said control means being arranged to operate said valve to stand in open position while said spray gun is traversing the area to be sprayed and to close said valve after said spray gun reaches said ends of the area to be sprayed and prior to arrival of the spray gun at its limits of traverse travel, said valve control means including a pair of individually positionally adjustable cams determining said ends and having sloping faces for gradual closing of said valve as said spray gun moves beyond said ends.

4. In a spray gun mover mechanism a reciprocating member arranged for mounting a spray gun thereon, means for moving said member to reciprocate a spray gun thereon in a traverse path, rod means mounted by end bearings to substantially parallel the path of said member in its reciprocative movements, cam means carried by said rod member and adapted to be adjustably xed thereon, low valve control means carried by said member and bearing against said cam means for control of said valve, and eccentric sleeve devices mounting said end bearings upon said rod means, said sleeve devices being separately adjustable at will to displace said rod means relative to said member for adjusting the operation of said cam means.

5. A spray gun mover mechanism comprising in combination with a spray gun, a stationary frame, a movable member shiftable upon said frame for mounting the spray gun to be reciprocatively movable therewith, power means connected to said member for moving the latter so as to reciprocate the gun relative to said frame, adjustable limit means controlling said power means to cause said gun to traverse a selectable area to be sprayed and also an area therebeyond at the end of each gun traverse stroke, a valve controlling inlet of compressed air to said spray 'gun for operation of the latter, control means for said valve, said valve and said control means being respectively fixed to the stationary frame and to the movable member, and said control means being adapted to operate said valve to stand in open position while said spray gun is traversing the area to be sprayed and to close said valve when said spray gun reaches the end limits of the spray area and prior to arrival of the spray gun at its selected limits of traverse travel.

6. A spray gun mover mechanism comprising a stationary frame, a rst gear rack mounted upon said frame for longitudinally shifting movements thereon, bracket means extending from said first gear rack for mounting the spray gun thereon to reciprocate with said gear rack relative to said stationary frame, a second gear rack xed to said stationary irame to extend in spaced parallel relation to said first gear rack, a gear disposed between said and second gear racks to extend in meshing relation therebetween, and a powered push-pull member pivotably connected at one of its ends to the center of said gear and extending therefrom into connection with a pushpull power source, whereby displacements of said push-pull member will force said gear to be displaced relative to said xed frame and to rotate due to its meshed connection with said second rack to thereupon drive said rst gear rack to move at twice the rate of movement of said pushpull member.

7. A spray gun mover mechanism comprising in combination with a spray gun, a member for mounting the spray gun to be reciprocatively movable therewith, a compressed air supply and a spray fluid supply for said gun, said uid supply being regulated by the pressure of the air supplied to said gun, substantially constant speed hydraulic power means connected to said member for moving the latter so as to reciprocate the gun to traverse the area to be sprayed and to move therebeyond at each end of the spray area, a variable delivery valve in said compressed air supply controlling inlet of compressed air to said spray gun for operation of the latter, control means for said valve, said valve and said control means being respectively connected to the stationary frame and to the movable structure and said control means being arranged to operate said valve to stand in open position while said spray gun is traversing the area to be sprayed and to close said valve when said spray gun reaches the end limits of the spray area and prior to arrival of the spray gun at its limits of traverse travel,

said valve control means including a pair of individually positionally adjustable cams each having a sloping contact face for slow closing of said valve as said gun moves beyond the end limits of said spray area, whereby the pressure of said air supplied to said gun is first reduced to terminate delivery of said fluid while continuing air flow through said gun and is then shut off to terminate operation of said gun.

8. In a spray gun mover mechanism a frame carrying a reciprocating member arranged for mounting a spray gun thereon, means for reciprocating said member for carrying a spray gun thereon in a traverse path, rod means mounted by end bearings upon said frame to substantially parallel the path of said member in its reciprocative movements, separately adjustable paired cam means carried in spaced relation by said rod means, valve means carried by said member and bearing respectively against said cam means prior to arrival at opposite ends of the traverse stroke for control of said valve means, and eccentric devices mounting the ends of said rod means upon said end bearings, said devices being separately adjustable at will to displace said rod means rela.- tive to said member for adjusting the operation of the cams.

9. A spray gun mechanism comprising a stationary frame, a spray gun, a movable member reciprocable upon said frame and mounting said spray gun to be reciprocably movable therewith, said gun having a compressed air supply and a spray uid supply, said fluid supply being regulated by the pressure of the air supplied to said gun, substantially constant speed fluid power means connected to said member for moving said gun relative to said frame, adjustable limit means controlling said power means to cause said gun to traverse a selectable area to be sprayed and also an area therebeyond at the end of each gun traverse stroke, rod means mounted by end bearings upon said frame to parallel the path of said member in its reciprocative movements, paired cams carried by said rod means and independently adjustably xed thereon in spaced relation, a variable delivery normally open valve in said compressed air supply controlling inlet of cornpressed air to said spray gun for operation of the latter, a control arm for said valve, said valve arm being mounted for movement with said gun and to bear respectively against said cams for closing said valve, said cams being positioned on said rod means to engage said valve arm prior to arrival of the gun at opposite ends of its stroke, eccentric sleeve devices mounting said end bearings upon the ends of said rod means and separately adjustable at will to displace said rod means relative to said member for additionally adjusting the operation of the cams, said cams each having a sloping contact face for slow closing of said valve as said gun moves beyond the area to be sprayed, whereby the pressure of said air supplied to said gun is rst reduced to terminate delivery of said uid while continuing air ow through said gun and is then shut oi to terminate operation of said gun.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,246,502 Bramsen et al June 24, 1941 2,369,424 Barlow Feb. 13, 1945 2,383,023 Sykes et al Aug. 21, 1945 2,505,179 Gaythwaite Apr. 25, 1950 2,610,605 Paasche Sept. 16, 1952 

